U.S. patent number 7,430,380 [Application Number 11/234,468] was granted by the patent office on 2008-09-30 for printing system.
This patent grant is currently assigned to Xerox Corporation. Invention is credited to Kristine A. German, Eric Scott Hamby, Robert M. Lofthus.
United States Patent |
7,430,380 |
Hamby , et al. |
September 30, 2008 |
Printing system
Abstract
A printing system includes first and second marking engines in
series which each include an image applying component for applying
an image to print media and a fixing device for at least partially
fixing the applied image. One or both marking engines are operable
in first and second modes of operation. In the first mode, the
fixing device at least partially fixes the image applied by the
respective image applying component. In the second mode, the fixing
device is used to further fix an image on the print media which has
been applied by the image applying component of the other marking
engine without an intermediate application of an image to the print
media by the second image applying component. A processing
component controls the marking engine to operate in a selected one
of the first and second modes of operation.
Inventors: |
Hamby; Eric Scott (Fairport,
NY), German; Kristine A. (Webster, NY), Lofthus; Robert
M. (Webster, NY) |
Assignee: |
Xerox Corporation (Norwalk,
CT)
|
Family
ID: |
37894119 |
Appl.
No.: |
11/234,468 |
Filed: |
September 23, 2005 |
Prior Publication Data
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|
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Document
Identifier |
Publication Date |
|
US 20070071465 A1 |
Mar 29, 2007 |
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Current U.S.
Class: |
399/45;
399/67 |
Current CPC
Class: |
G03G
15/2021 (20130101); G03G 15/50 (20130101); G03G
15/2014 (20130101); G03G 15/20 (20130101); G03G
2215/2074 (20130101); G03G 2215/2083 (20130101); G03G
2215/00805 (20130101); G03G 2215/00021 (20130101); G03G
2215/209 (20130101); G03G 2215/0119 (20130101); G03G
2215/0081 (20130101); G03G 2215/20 (20130101) |
Current International
Class: |
G03G
15/00 (20060101); G03G 15/20 (20060101) |
Field of
Search: |
;399/2,45,67,68,69,82,107,122,79,320,322,328,341,400,401,407 |
References Cited
[Referenced By]
U.S. Patent Documents
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Primary Examiner: Gray; David M.
Assistant Examiner: Do; Andrew V
Attorney, Agent or Firm: Palazzo; Eugene O. Fay Sharpe
LLP
Claims
The invention claimed is:
1. A printing system comprising: a first marking engine comprising
a first image applying component for applying an image to print
media and a first fixing device for at least partially fixing the
image applied by the first image applying component; a second
marking engine in series with the first marking engine, the second
marking engine comprising a second image applying component and a
second fixing device, the second marking engine being operable in a
first mode of operation in which the second image applying
component applies an image to print media and the second fixing
device at least partially fixes the image applied by the second
image applying component, the second marking engine being operable
in a second mode of operation in which the second fixing device
further fixes an image on the print media which has been applied by
the first image applying component and fixed by the first fixing
device without an intermediate application of an image to the print
media by the second image applying component; and a processing
component which controls the second marking engine to operate in a
selected one of the first and second modes of operation.
2. The printing system of claim 1, wherein the second marking
engine further comprises a bypass pathway whereby print media with
images which have been applied by the first image applying
component and fixed by the first fixing device bypass the second
image applying component in the second mode of operation.
3. The printing system of claim 1, wherein the first marking engine
is operable in both a first mode of operation and second mode of
operation, in the first mode of operation, the first image applying
component applies images to print media and the first fixing device
fixes the images applied by the first image applying component, in
the second mode of operation, the first fixing device further fixes
images which have been applied by the second image applying
component and fixed by the second fixing device.
4. The printing system of claim 1, wherein the processing component
determines whether to operate the second marking engine in a
selected one of the first and second modes based on at least one
of: a property of the print media to be printed; a number of sheets
to be printed consecutively on the first marking engine; an
estimate of toner pile height of the image; a selected gloss level
of the image; and a shortfall in fixing capacity of the first
marking engine.
5. The printing system of claim 1, wherein in the second mode of
operation, the processing component identifies the second marking
engine from a plurality of available second marking engines based
on at least one selection criterion.
6. The printing system of claim 1, wherein the processing component
determines a setpoint for the second fixing device for the second
mode of operation which differs from a setpoint for the second
fixing device for the first mode of operation.
7. The printing system of claim 6, wherein the setpoint includes at
least one of the group consisting of a temperature setpoint, a
dwell time set point, and a pressure setpoint.
8. The printing system of claim 1 wherein the first image applying
component is of a different print modality from the second image
applying component.
9. A method of marking print media comprising: applying an image to
print media with a first image applying component and at least
partially fixing the image with an associated first fixing device;
and further fixing the applied and at least partially fixed image
with a second fixing device associated with a second image applying
component configured for selectively applying images to print
media, without an intermediate application of an image to the print
media by the second image applying component.
10. The method of claim 9, further comprising: directing the print
media with the applied and at least partially fixed image to a
bypass pathway which bypasses the second image applying
component.
11. The method of claim 9, further comprising: conveying the print
media between the first and second fixing devices on a print media
conveyor.
12. The method of claim 9, further comprising: determining whether
to further fix the print media with the applied and at least
partially fixed image based on at least one of: a property of the
print media to be marked; a number of sheets of the print media to
be fixed consecutively on the first fixed device; an estimate of
toner pile height of the image; a selected gloss level of the
image; and a shortfall in fixing capacity of the first fixing
device.
13. The method of claim 9, further comprising: selecting the second
fixing device from a plurality of available second fixing devices
based on at least one selection criteria.
14. The method of claim 9, further comprising: adjusting a setpoint
of the second fixing device from a first setpoint for fixing
unfused images to a second setpoint for further fixing the image on
the print media which has been applied by the first image applying
component and fixed by the first fixing device.
15. The method of claim 9, further comprising: in a first mode of
operation, applying a second image to print media with the second
image applying component and fixing the second image with the
second fixing device; and in a second distinct mode of operation,
with the second fixing device, further fixing the image applied by
the first image applying component and at least partially fixed by
the first fixing device.
16. The method of claim 15, further comprising: in the first mode
of operation, the application of the second image to print media
with the second image applying component and the fixing of the
second image with the second fixing device are performed generally
contemporaneously with applying the first image to print media with
the first image applying component and fixing the first image with
the first fixing device.
17. The method of claim 9, wherein the second fixing device
increases at least one of: the gloss of the image applied by the
first image applying component and at least partially fixed by the
first fixing device; and the permanency of the image.
18. The method of claim 9, wherein the print media is outside the
latitude limits of the first fixing device.
19. The method of claim 9, wherein the first fixing device effects
only a partial fixing of the image.
20. A printing system comprising: a first marking engine comprising
a first image applying component for applying an image to print
media and a first fixing device for at least partially fixing the
image applied by the first image applying component; a second
marking engine in series with the first marking engine, the second
marking engine comprising a second image applying component for
applying an image to print media and a second fixing device for at
least partially fixing the image applied by the second image
applying component, and a bypass pathway whereby the second image
applying component is selectively bypassed for further fixing an
image on the print media which has been applied by the first image
applying component and fixed by the first fixing device.
21. The printing system of claim 20, further comprising: a
processing component which selectively controls a switch which
routes the print media to the bypass pathway.
Description
CROSS REFERENCE TO RELATED PATENTS AND APPLICATIONS
U.S. application Ser. No. 10/761,522, filed Jan. 21, 2004, entitled
"HIGH RATE PRINT MERGING AND FINISHING SYSTEM FOR PARALLEL
PRINTING," by Barry P. Mandel, et al.;
U.S. application Ser. No. 10/785,211, filed Feb. 24, 2004, entitled
"UNIVERSAL FLEXIBLE PLURAL PRINTER TO PLURAL FINISHER SHEET
INTEGRATION SYSTEM," by Robert M. Lofthus, et al.;
U.S. application Ser. No. 10/881,619, filed Jun. 30, 2004, entitled
"FLEXIBLE PAPER PATH USING MULTIDIRECTIONAL PATH MODULES," by
Daniel G. Bobrow.;
U.S. application Ser. No. 10/917,768, filed Aug. 13, 2004, entitled
"PARALLEL PRINTING ARCHITECTURE CONSISTING OF CONTAINERIZED IMAGE
MARKING ENGINES AND MEDIA FEEDER MODULES," by Robert M. Lofthus, et
al.;
U.S. application Ser. No. 10/924,106, filed Aug. 23, 2004, entitled
"PRINTING SYSTEM WITH HORIZONTAL HIGHWAY AND SINGLE PASS DUPLEX,"
by Lofthus, et al.;
U.S. application Ser. No. 10/924,113, filed Aug. 23, 2004, entitled
"PRINTING SYSTEM WITH INVERTER DISPOSED FOR MEDIA VELOCITY
BUFFERING AND REGISTRATION," by Joannes N.M. deJong, et al.;
U.S. application Ser. No. 10/924,458, filed Aug. 23, 2004, entitled
"PRINT SEQUENCE SCHEDULING FOR RELIABILITY," by Robert M. Lofthus,
et al.;
U.S. application Ser. No. 10/924,459, filed Aug. 23, 2004, entitled
"PARALLEL PRINTING ARCHITECTURE USING IMAGE MARKING ENGINE MODULES
(as amended)," by Barry P. Mandel, et al;
U.S. application Ser. No. 10/953,953, filed Sep. 29, 2004, entitled
"CUSTOMIZED SET POINT CONTROL FOR OUTPUT STABILITY IN A TIPP
ARCHITECTURE," by Charles A. Radulski et al.;
U.S. application Ser. No. 10/999,450, filed Nov. 30, 2004, entitled
"ADDRESSABLE FUSING FOR AN INTEGRATED PRINTING SYSTEM," by Robert
M. Lofthus, et al.;
U.S. application Ser. No. 11/000,168, filed Nov. 30, 2004, entitled
"ADDRESSABLE FUSING AND HEATING METHODS AND APPARATUS," by David K.
Biegelsen, et al.;
U.S. application Ser. No. 11/001,890, filed Dec. 2, 2004, entitled
"HIGH RATE PRINT MERGING AND FINISHING SYSTEM FOR PARALLEL
PRINTING," by Robert M. Lofthus, et al.;
U.S. Pat. No. 6,925,283, issued Aug. 2, 2005, entitled "HIGH PRINT
RATE MERGING AND FINISHING SYSTEM FOR PARALLEL PRINTING," by Barry
P. Mandel, et al.;
U.S. application Ser. No. 11/090,498, filed Mar. 25, 2005, entitled
"INVERTER WITH RETURN/BYPASS PAPER PATH," by Robert A. Clark;
U.S. application Ser. No. 11/095,872, filed Mar. 31, 2005, entitled
"PRINTING SYSTEM," by Paul C. Julien;
U.S. application Ser. No. 11/094,864, filed Mar. 31, 2005, entitled
"PRINTING SYSTEM," by Jeremy C. dejong, et al.;
U.S. application Ser. No. 11/094,998, filed Mar. 31, 2005, entitled
"PARALLEL PRINTING ARCHITECTURE WITH PARALLEL HORIZONTAL PRINTING
MODULES," by Steven R. Moore, et al.;
U.S. application Ser. No. 11/109,566, filed Apr. 19, 2005, entitled
"MEDIA TRANSPORT SYSTEM," by Mandel et al.; and
U.S. application Ser. No. 11/170,845, filed Jun. 30, 2005, entitled
"HIGH AVAILABILITY PRINTING SYSTEMS," by Meera Sampath et al.
BACKGROUND
The present exemplary embodiment relates generally to fusing of
images in a printing system including a plurality of marking
engines. It finds particular application in conjunction with a
printing system which includes first and second tandem marking
engines where the second marking engine receives print media which
has been partially fused by the fuser of the first marking engine,
and will be described with particular reference thereto. However,
it is to be appreciated that the present exemplary embodiment is
also amenable to other like applications.
In a typical xerographic marking engine, such as a copier or
printer, a photoconductive insulating member is charged to a
uniform potential and thereafter exposed to a light image of an
original document to be reproduced. The exposure discharges the
photoconductive insulating surface in exposed or background areas
and creates an electrostatic latent image on the member, which
corresponds to the image areas contained within the document.
Subsequently, the electrostatic latent image on the photoconductive
insulating surface is made visible by developing the image with a
developing material. Generally, the developing material comprises
toner particles adhering triboelectrically to carrier granules. The
developed image is subsequently transferred to a print medium, such
as a sheet of paper. The fusing of the toner onto the paper is
generally accomplished by applying heat to the tonerwith a heated
roller and application of pressure.
Systems which incorporate several marking engines have been
developed. These systems enable high overall outputs to be achieved
by printing portions of the same document on multiple printers.
Such systems are commonly referred to as "tandem engine" printers,
"parallel" printers, or "cluster printing" (in which an electronic
print job may be split up for distributed higher productivity
printing by different printers, such as separate printing of the
color and monochrome pages). Tandem engine printing systems allow a
sheet of print media to be printed by a first marking engine and
then conveyed by a paper pathway to a second marking engine. This
permits "tandem duplex printing." In this process, a first marking
engine applies an image to a first side of a sheet and a second
marking engine applies an image to a second side of the sheet. Each
of the marking engines is thus operating in a simplex mode to
generate a duplex print.
Such integrated printing systems have advantages over more complex,
single marking engine systems in that they can achieve high
productivity by combining several relatively low-cost smaller
marking engines. However, the smaller marking engines frequently do
not have the capability to fuse a wide range of print substrates or
may run at lower outputs, in terms of prints per minute, when
certain heavyweight media is to be fused.
INCORPORATION BY REFERENCE
The following references are totally incorporated herein in their
entireties, by reference:
U.S. Pat. No. 6,925,283 issued Aug. 2, 2005, entitled "HIGH PRINT
RATE MERGING AND FINISHING SYSTEM FOR PARALLEL PRINTING," by Barry
P. Mandel, et al. discloses a media path system operable to
transport printed media from two or more marking engines to one or
more finishing stations such that the streams are merged and
transported one on top of the other.
US 2005/0135847 published Jun. 23, 2005, entitled "MODULAR
MULTI-STAGE FUSING SYSTEM," by Gregory V. Bogoshian discloses a
multi-stage fusing system for fixing toner images to copy
substrates of various weights.
BRIEF DESCRIPTION
In aspects of the exemplary embodiment, a printing system and a
method of printing are provided. In one aspect, the printing system
includes a first marking engine including a first image applying
component for applying an image to print media and a first fixing
device for at least partially fixing the image applied by the first
image applying component. A second marking engine is in series with
the first marking engine. The second marking engine comprises a
second image applying component and a second fixing device. The
second marking engine being operable in a first mode of operation
in which the second image applying component applies an image to
print media and the second fixing device at least partially fixes
the image applied by the second image applying component. The
second marking engine is also operable in a second mode of
operation in which the second fixing device further fixes an image
on the print media which has been applied by the first image
applying component and fixed by the first fixing device without an
intermediate application of an image to the print media by the
second image applying component. A processing component controls
the second marking engine to operate in a selected one of the first
and second modes of operation.
In another aspect, a method of marking print media includes
applying an image to print media with a first image applying
component and at least partially fixing the image with an
associated first fixing device. The applied and at least partially
fixed image is further fixed with a second fixing device associated
with a second image applying component configured for selectively
applying images to print media, without an intermediate application
of an image to the print media by the second image applying
component.
In another aspect, a printing system includes a first marking
engine comprising a first image applying component for applying an
image to print media and a first fixing device for at least
partially fixing the image applied by the first image applying
component. A second marking engine is in series with the first
marking engine. The second marking engine includes a second image
applying component for applying an image to print media and a
second fixing device for at least partially fixing the image
applied by the second image applying component. A bypass pathway is
provided whereby the second image applying component is selectively
bypassed for further fixing an image on the print media which has
been applied by the first image applying component and fixed by the
first fixing device.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic side view of a printing system according to
one aspect of the exemplary embodiment;
FIG. 2 is an enlarged schematic side view of one of the marking
engines of FIG. 1; and
FIG. 3 is a block diagram of the printing system of FIG. 1
illustrating an exemplary control system.
DETAILED DESCRIPTION
Printing systems having multiple marking engines provide a wide
range of printing capabilities with high reliability and often have
excess capacity so that urgent print jobs can be handled
efficiently. During normal operation, typically fewer than all the
marking engines of such a printing system are occupied in printing
print media. The present exemplary embodiment enables the excess
capacity of such a system to be utilized to provide a secondary
fusing of print media which has been only partially fused in one of
the operational marking engines.
Aspects of the exemplary embodiment relate to a printing system
comprising first and second marking engines in series, each with an
image applying component for applying images to print media. A
fixing device is associated with each marking engine. In one mode
of operation, the image applying component of the second making
engine can by bypassed to enable media which has been fixed by the
first fixing device to be further fixed by the second fixing device
without intermediate application of a second image to the print
media. For example, a print media conveyor system includes a first
pathway for conveying print media to the second image applying
component and a second pathway which allows print media to bypass
the second image applying component. Alternatively, the image
applying component may be dissociated from the conveyor system when
not in use. The print media can be conveyed between the first and
second fixing devices by a print media conveyor. In another aspect,
a control system selects fused images forfurther fixing and routes
them to the fixing device associated with an otherwise unoccupied
second marking engine for further fixing.
The exemplary printing system allows a marking engine which is not
being used for marking images to be utilized for applying the
further fixing treatment. The further fixing treatment can be used
to reduce the requirements on the first fixing device by allowing
the first fixing device to effect only a partial fixing. The
further fixing treatment may be used to increase image permanence
(attachment of the image), to modify image appearance (gloss), or
both.
The exemplary printing system may have an improved print media
latitude, for example, enabling heavy weight paper which is outside
the normal latitude limits of any of the individual marking engines
to be printed and fixed. Alternatively, print media which is within
the latitude limits of an individual marking engine but which is
normally run at slower speeds can be handled at higher
productivity. In another aspect, the printing system takes
advantages of particular attributes of the second fixing device
which may be temporarily or permanently lacking in the first fixing
device to achieve particular fixing characteristics. For example,
the secondary fixing device may have a capacity for higher gloss
than the first fixing device. The control system may access a model
of the machine which includes information on the capabilities of
each of the fixing devices in the printing system such that an
appropriate secondary fixing device from a plurality of available
secondary fixing devices may be selected which best satisfies
desired fixing characteristics of a print job or which is best
suited for handling a selected print media.
Print media which has been fixed by a first fixing device may have
residual heat when it arrives at a second fixing device. The second
fixing device may be set at a lower temperature to compensate for
the residual heat. A model of the print media temperature upon
arrival at the second fixing device may be used by a processing
system of the printing system to adjust the operating temperature
of the second fixing device.
The image applying components of the two marking engines used for
primary and secondary fixing can be of the same or of different
print modalities, e.g., both monochrome (black or custom color),
both process color (multicolor, such as CMYK), or one of each.
Thus, a color image may receive its second fixing by the fixing
device of a black marking engine, or vice versa, although in
general, a second fixing is performed by a marking engine of the
same print modality, since the operating conditions are generally
better matched for the marking material.
In another aspect a method of marking includes marking print media
with a first marking engine and applying a fixing treatment to the
image with an associated fixing device. A further fixing treatment
is applied to the marked print media by a fixing device associated
with a second marking engine. In one aspect, a processing component
directs the print media to a bypass pathwayfor bypassing an image
applying component of the second marking engine.
The terms "marking engine" and "printer," are used interchangeably
to refer to a device for applying an image to print media. "Print
media" can be a usually flimsy physical sheet of paper, plastic, or
other suitable physical print media substrate for images, whether
precut or web fed. The printing system may include a variety of
other components, such as finishers, paper feeders, and the like,
and may be embodied as a copier, printer, or a multifunction
machine. A "print job" or "document" is normally a set of related
sheets, usually one or more collated copy sets copied from a set of
original print job sheets or electronic document page images, from
a particular user, or otherwise related.
The printing system may incorporate "tandem engine" printers,
"parallel" printers, "cluster printing," "output merger," or
"interposer" systems, and the like, as disclosed, for example, in
U.S. Pat. Nos. 4,579,446; 4,587,532; 5,326,093; 5,489,969
5,568,246; 5,570,172; 5,596,416; 5,995,721; 6,554,276, 6,654,136;
6,607,320, and in above-mentioned application Serial Nos.
10/924,459 and 10/917,768, the disclosures of which are totally
incorporated herein by reference. A tandem engine printing system
feeds paper from a common paper stream to a plurality of printers
in series, which may be horizontally and/or vertically stacked.
Printed media from the various printers is then taken from the
printers to a finisher where the sheets associated with a single
print job are assembled.
With reference to FIG. 1, an exemplary printing system 10 for
effecting a dual fusing of an image is illustrated. The printing
system may be a printer, copier, or a multifunction device having
both printing and copying capabilities. The illustrated printing
system is a modular system and includes a plurality of processing
units, such as a print media source 12, a plurality of marking
engines 14, 16, 18, and an output destination 20, such as a
finisher. The processing units 12, 14, 16, 18, and 20 are all
interconnected by a print media conveyor 22. In some embodiments,
one or more of the processing units 12, 14, 16, 18, 20 are
removable processing units. For example, the functional portion of
a processing unit may be removed, leaving only the external housing
or mounting fixture through which the print media conveyor 22
passes. In this manner, for example, the functional portion can be
removed for repair, or can be replaced to effectuate an upgrade or
modification of the printing system 10.
The printing system 10 executes print jobs. Print job execution
involves printing images, such as selected text, line graphics,
photographs, machine ink character recognition (MICR) notation, and
the like on front, back, or front and back sides or pages of one or
more sheets of paper or other print media. Some sheets may be left
completely blank. Some sheets may have both color and monochrome
images. Execution of the print job may also involve collating the
sheets in a certain order. Still further, the print job may include
folding, stapling, punching holes into, or otherwise physically
manipulating or binding the sheets. The printing, finishing, paper
handing, and other processing operations that can be executed by
the printing system 10 are determined by the capabilities of the
paper source 12, marking engines 14, 16, 18, and finisher 20 of the
printing system 10. These capabilities may increase over time due
to addition of new processing units or upgrading of existing
processing units. The capabilities may also decrease overtime due
to failure or removal of one or more processing units.
While three marking engines 14, 16, 18 are illustrated, the number
of marking engines can be two, three, four, five, six, or more.
Marking tasks can be distributed amongst the at least two marking
engines. Some or all of the marking engines 14, 16, 18 may be
identical to provide redundancy or improved productivity through
parallel printing. Alternatively or additionally, some or all of
the marking engines 14, 16, 18 may be of different modalities to
provide different capabilities. Thus, while three multi-color
(process color, P) marking engines are illustrated, one or more of
the marking engines 14, 16, 18 may be a monochrome engine, such as
a black (K) marking engine or a custom color (C) marking
engine.
The illustrated marking engines 14, 16, 18 employ xerographic
printing technology, in which an electrostatic image is formed and
coated with a toner material, and then transferred and fused to
paper or another print medium by application of heat and/or
pressure. However, marking engines employing other printing
technologies can be provided as processing units, such as marking
engines employing ink jet transfer, thermal impact printing, or the
like.
The illustrated print media source 12 is a high capacity feeder
which includes print media sources 24, 26, 28, 30, such as trays,
which are connected with the print media conveyor 22 to provide
selected types of print media to all of the marking engines. While
four print media sources are illustrated, the number of print media
sources can be one, two, three, four, five, or more. In other
embodiments, one or more of the marking engines may include its own
dedicated print media source. Each of the print media sources 24,
26, 28, 30 can store sheets of the same type of print medium, or
can store different types of print media. The print media can be
substantially any type of medium upon which one or more of the
marking engines 12, 14, 16 can print, such as: high quality bond
paper, lower quality "copy" paper, overhead transparency sheets,
high gloss paper, heavy weight paper and card, and the like. A
given marking engine 12, 14, 16 may be able to print and fix one
type of print media without slowing from its normal (e.g., maximum)
operating speed while for another type of print media, only a
partial fixing is effected when the marking engine is run at a
normal operating speed. While the marking engine may be able to
accommodate these media by slowing, this affects the productivity
of the printing system. In such cases, a secondary fixing operation
in a separate marking engine allows the first marking engine to
maintain normal operating speed.
For example, print media source 24 may store a first weight paper
such as letter size paper weighing 75 gsm, print media source 26
may store a second weight paper such as letter size paper weighing
90 gsm, print media source 28 may store a third weight paper such
as letter size paper weighing 120 gsm, and print media source 30
may store a fourth weight paper or card such as letter size paper
weighing 300 gsm.
Depending on the capabilities of the marking devices, these weights
may be considered normal or heavyweight. In an exemplary
embodiment, the print media in sources 24 and 26 is normal paper
for all the color marking engines, i.e., the marking engines 14, 16
and 18 can print on these media types under normal operating
conditions, without slowing. The print media in source 28 may be
utilized if the marking engine is run at a slower speed or if a
further fixing treatment is applied. The print media in source 30
may be outside the fixing capabilities of any of the color marking
engines, even when run at a slower than normal speed, and in order
to fix such media, a secondary fixing treatment is applied.
The print media conveyor 22 is controllable to acquire sheets of a
selected print medium from the print media sources 24, 26, 28, 30,
transfer each acquired sheet to one or more of the installed
marking engines 14, 16, 18 to perform selected marking tasks, and
then transfer each sheet to the finisher 20 to perform finishing
tasks. The finisher unit 20 includes one or more print media output
destinations, 32, 34, 36, herein illustrated by trays. While three
output destinations 32, 34, 36 are illustrated, the printing system
10 may include one, two, three, four, or more print media output
destinations.
The print media conveyor 22 includes a plurality of paper paths and
associated drive elements, such as rollers, spherical balls, or air
jets, which convey the print media along the paths and may include
diverters, inverters, interposers, and the like, as known in the
art. The paths may be in the form of loops which allow print media
from one marking engine to be delivered to another marking engine
for duplex printing (two sided printing) or overprinting (printing
on the same side of the sheet). In the illustrated printing system
10, print media which has been printed by one marking engine can be
routed to any other marking engine. Additionally, bypass pathways
allow any one or more of the marking engines to be bypassed. In
other configurations (not shown) the routing may be more limited.
In the exemplary embodiment, main downstream and upstream highways
38, 40, respectively, are connected at ends thereof by junctions
42, 44, while a second, optional downstream highway 46 is
accessible from the first downstream highway 38 for bypassing one
or more of the marking engines 14, 16, 18. Branch pathways 50, 52
connect the main downstream highway 38 with respective ones of the
marking engines. While the illustrated marking engines are aligned
in a linear arrangement, it is also contemplated that they may be
stacked in a two or three dimensional configuration.
At least one paper source 24, 26, 28, 30 is connected by the
conveyor 22 with at least two marking engines of the same type,
such as process color marking engines 14, 16, and 18. In a first
mode of operation, a print job or jobs employing the paper can be
selectively distributed to two or more of the marking engines 14,
16, 18 for parallel printing (two or more marking engines each
performing part of a print job) or to two or more marking engines
in series for duplex printing or overprinting. In this mode, both
marking engines apply and fix an image. In a second mode of
operation, print media marked and fixed by a first of the marking
engines 14, 16, 18 is conveyed to a second of the marking engines
14, 16, 18 for a further fixing without marking. The printing
system may be capable of operating in both these modes
contemporaneously or during a single print job, depending on the
number of available marking engines. For example, marking engine 18
may be simplex printing a first portion of a print job on normal
weight paper while marking engines 14 and 16 operate in series to
simplex print and fix, then further fix heavy weight media.
For higher basis weight print media, where a marking engine does
not adequately fix the image at normal operating speeds, the first
fixing device may perform a partial fixing adequate to at least
tack the image to the sheet, with the second fixing device
completing the fixing to achieve long term image permanence. While
printing of heavy paper weight is used as an example of an
application to which the dual fusing mode is suited, it will be
appreciated that other properties of the print media, such as
surface texture and coatings, and properties of the image, such as
toner pile height and area coverage may, in some instances, also
benefit from the dual fusing mode in extending the capabilities of
the printing system or its productivity. In the case of rough
stock, the toner may adhere poorly to crevices in the paper surface
and the flow of toner may be insufficient. A further fixing tends
to improve adherence. For coated papers, a higher gloss may be
desired is that the image meets the gloss of the surrounding page.
This can be achieved in the secondary fixing.
In the illustrated embodiment, any of the marking engines can be
used as a second fixing device for applying a further fixing to a
print media image which has been at least partially fixed by a
fixing device of any other marking engine. In other embodiments, it
is contemplated that fewer than all of the marking engines may be
configured for serving as a second fixing device and/or that the
pathways of the conveyor system 22 may permit fewer than all
possible combinations of marking engines to be used as first and
second fixing devices.
With reference also to FIG. 2, which illustrates one of the marking
engines 14, by way of example, the marking engines each include an
image applying component 54, for applying an image to the print
media, and a fixing device 56, for fixing the applied image to the
print media. Marking engines 16 and 18 may be similarly configured.
In the case of a xerographic marking engine, for example, the
marking engine includes various xerographic subsystems for forming
an image, transferring the image to a sheet of paper, and fusing
the image to attach the image more permanently to the print media.
The marking engine of a xerographic system typically includes a
charge retentive surface, such as a rotating photoreceptor 60 in
the form of a belt or drum. The images are created on a surface of
the photoreceptor. Disposed at various points around the
circumference of the photoreceptor 60 are the xerographic
subsystems, which include a charging station 62 for one or more of
the colors to be applied, such as a charging corotron, an exposure
station 64, which forms a latent image on the photoreceptor, such
as a Raster Output Scanner (ROS) or LED bar, a developer unit 66,
associated with each charging station 62 for developing the latent
image formed on the surface of the photoreceptor by applying a
toner to obtain a toner image, a transfer unit 68, such as a
transfer corotron, transfers the toner image thus formed to the
surface of a print media substrate, such as a sheet of paper, or/to
an intermediate transfer belt. In the illustrated embodiment, each
of four toners cyan, magenta, yellow, and black (CMYK) is applied
to a separate photoreceptor 60, and the resulting image transferred
to an intermediate transfer belt 70. When the marking engine is
operating in a normal marking and fixing mode, print media is
directed by a switch 72 in pathway 50 to a transfer point defined
by nip 74 between rollers 76, 78, as indicated by arrow A. At the
transfer point 74, the print media is brought into contact with the
intermediate transfer belt 70 for transfer of the image to the
print media. Thereafter, the imaged print media is conveyed to the
fixing device 56.
In an alternative embodiment (not shown) the charging station 62,
exposure station 64, and developer unit 66 for each of the four
toners are spaced around the same photoreceptor. In this
embodiment, no intermediate transfer belt is required and the
transfer point 74 can be the point at which the toner is
transferred from the photoreceptor to the print media. A marking
engine of this type is disclosed, for example, in above-mentioned
copending application Ser. No. 11/137,251, incorporated herein by
reference. In any particular embodiment of an electrophotographic
marking engine, there may be variations on this general outline,
such as additional corotrons, cleaning devices, and the like.
The fixing device 56, which is known as a fuser in electrographic
printing systems, generally applies at least one of heat and
pressure to the sheet to physically attach the toner and optionally
to provide a level of gloss to the printed media. The illustrated
fixing device includes a heated roller 80 and a pressure roller 82,
which define a nip 84 therebetween through which the substrate
passes. Fixing devices which apply ultraviolet radiation, or other
radiation to fix the marking material to the substrate are also
contemplated, as disclosed, for example, in copending U.S.
application Ser. No. 11/168,152, filed Jun. 28, 2005, entitled
"ADDRESSABLE IRRADIATION OF IMAGES," by Kristine A. German, et al.,
which is incorporated herein by reference in its entirety.
The xerographic subsystems 62, 64, 66, 68 are controlled by a
processing component, which may be located in the marking engine
and/or elsewhere in the printing system 10. In the embodiment
illustrated in FIG. 3, the processing component is distributed over
the printing system and includes a marking engine controller 90
such as a CPU, associated with each marking engine 14, 16, 18,
which includes actuators for controlling each of the subsystems,
and an overall control system 92, which communicates with the
individual marking engine CPUs 90 as described in greater detail
below. The marking engine controller 90 is linked to the system
controller 92 and may be also linked to other known components,
such as a memory, a marking cartridge platform, a marking driver, a
function switch, a self-diagnostic unit, all of which can be
interconnected by a data/control bus. Each marking engine 14,16,18
may have its own marking engine controller 90, as shown in FIG.
3.
The printing system 10 is configured such that at least one of the
fixing devices in the printing system is capable of serving as a
secondary fixing device. For example, at a given time, the fixing
device 56 of marking engine 14 may serve as a primary fixing device
for print media marked by image applying component 54. The marked
and at least partially fixed media is transferred by downstream
highway 38 to the second marking engine 16 where no image is
applied by the image applying component 94 (FIG. 1). However, the
fixing device 95 of marking engine 16, acting in the capacity of a
secondary fixing device, further fixes the image. It will be
appreciated that the function of any marking engine may change over
time such that at one time it operates in a marking and fixing mode
and at another time in a fixing only mode.
In one embodiment, at least one of the marking engines 14, 16, 18
includes a bypass pathway 96 (FIG. 2) which allows the print media
to bypass the transfer point 74. In the fixing only mode, the
switch 72 is set so as to direct printed media which arrives from
another marking engine via pathway 50 onto pathway 96 as indicated
by arrow B. Pathway 96 connects pathway 50 directly with the fixing
device 56, bypassing the transfer point 74. This facilitates
operating the marking engine solely as a secondary fixing device.
The movement of transfer belt 70 may be stopped or reduced while
the marking engine functions as a secondary fixing device.
In another embodiment, in which bypass pathway 96 may be omitted,
the transfer point 74 may be bypassed by spacing the transfer belt
70 from the paper pathway 50. For example, roll 78 may be lifted to
bring the transfer belt 70 out of contact with roll 80, allowing
the print media to pass by without contacting the transfer belt or
with only a low pressure contact. This reduces the chance for
partially fused toner to be transferred from the print media to the
transfer belt 76 and allows movement of the transfer belt to be
stopped.
In yet another embodiment, one or more of the marking engines 14,
16, 18 is capable of functioning as a secondary fixing device
without modification to the paper paths.
The fixing devices 56, 95 of each of the marking engines may be
substantially identical, or may be different due to machine to
machine variations in nominally identical devices or due to
differences in design and construction of the fixing devices. The
differences in fusing capabilities may be comprehended by the
printing system 10 and utilized in determining when to apply a
secondary fixing treatment and which marking engine to utilize. In
one aspect, the printing system includes at least one marking
engine which has enhanced fixing capabilities. This marking engine
can be used by the printing system as the secondary fixing device
when the enhanced fusing capabilities are selected. In another
aspect, differences in properties the fuser roll of the fixing
device may be utilized. For example, a black marking engine
typically has a hard fuser roll to provide an extended life where
gloss of the images is not generally of concern, while a color
marking engine may have a softer fuser roll for achieving a higher
gloss, at the expense of a shorter life. Where high gloss black
images are desired, the fixing device of a color printer may be
used to increase the gloss.
When a marking engine 14, 16, 18 is operating in a fixing only
mode, the marking engine controller 90 may communicate with one or
more of the marking engine subcomponents 62, 64, 66, 68 to place
the subcomponent in a mode adapted to reduce wear on the
subcomponent and ensure that high quality prints can be generated
once the marking engine returned to a marking and fixing mode. For
example, periodic application of toner may be made from the
developer housing 66 onto the photoreceptor 60 and cleaned
therefrom to avoid degradation of the toner in the developer
housing. Power to one or more of the subcomponents may be reduced.
The transfer belt 70 may be stopped.
As illustrated in FIG. 3, an image input device supplies the
printing system 10 with images to be printed. The image input
device can be a built-in optical scanner 100 and/or digital network
102. The scanner can be used to scan a document such as book pages,
a stack of printed pages, or the like, to create a digital image of
the scanned document that is reproduced by printing operations
performed by the printing system 10. A print job can be
electronically delivered from the digital network 102, as
illustrated in FIG. 3. The image input device 100, 102 communicates
with the main control system 92 of the printing system 10. The
digital network 102 may interconnect, for example, personal
computers or other digital devices (not shown). For example, a
network user operating word processing software running on a
network computer may select to print a word processing document on
the printing system 10, thus generating the print job, or an
external scanner (not shown) connected to the network 102 may
provide the print job in electronic form. While a wired network
connection 104 is illustrated, a wireless network connection or
other wireless communication pathway may be used instead or
additionally to connect the printing system 10 with the digital
network 102 or scanner 100. The digital network 102 can be a local
area network such as a wired Ethernet, a wireless local area
network (WLAN), the Internet, some combination thereof, or the
like. Moreover, it is contemplated that print jobs may be delivered
to the printing system 10 in other ways, such as by using an
optical disk reader (not illustrated) built into the printing
system 10, or by using a dedicated computer connected only to the
printing system 10.
With continued reference to FIG. 3, the processing component of the
printing system will be described in greater detail. The control
system 92 includes a scheduling system 110, which includes various
processing components for ordering print jobs into a queue and
selecting appropriate marking engines and other components of the
printing system 10 to perform the steps in generating each sheet.
An example of one suitable scheduling system is described in
copending U.S. application Ser. No. 11/137,251, filed May 25, 2005,
entitled "SCHEDULING SYSTEM," by Robert M. Lofthus et al., which is
incorporated herein by reference in its entirety. In selecting a
suitable job order and processing components for a job, the
scheduling system accesses a model of the machine 112 to obtain
information on the printing system for scheduling jobs. In
particular, the model of the machine may provide information on the
functional characteristics of the marking engines, the current
states of the marking engines, and their future availability. In
this way, the scheduling system 110 can identify an available
marking engine to be used for a secondary fixing of already marked
sheets from those marking engines which are identified by the model
112 as having availability during the desired time period. Where
more than one marking engine is available for performing the
secondary fixing, the scheduling system may use inbuilt selection
criteria and/or user input selection criteria to select a marking
engine which best fits the criteria. For example, the scheduling
system may select the least utilized marking engine or a marking
engine which currently has no marking capability or one which has
particular fixing characteristics.
In determining when to apply a secondary fixing treatment, the
scheduling system may take into account such factors as: 1.
Properties of the print media, such as the basis weight of the
media to be printed, any coatings thereon, and surface properties,
such as roughness. In such instances, the scheduling system may
schedule a secondary fixing device for completing the fixing of
such pages. 2. The number of sheets to be printed consecutively. If
more than a maximum number of heavy weight sheets are to be fixed,
for example, the temperature of the first fixing device may drop
below an accepted level if run at normal operating speeds. In such
instances, the scheduling system may employ a secondary fixing
device to complete the fixing of the partially fused sheets. 3.
Properties of the image, such as the estimated toner pile height.
Fortoner pile heights above a certain level the first fixing device
may not be able to fix the image at normal operating speeds. In
such instances, the scheduling system may schedule a secondary
fixing device for completing the fixing of such pages. The pile
height may be estimated from the density of each toner to be
overlapped in a given area of the image. 4. The specified gloss
level to be achieved. When a high gloss is specified, a marking
engine may not provide the desired gloss for the image at normal
operating speeds. In such instances, the scheduling system may
schedule a first fixing device to perform a partial fixing adequate
to at least tack the image to the sheet, with the second fixing
device achieving the desired gloss. 5. The state of a marking
engine. While the exemplary embodiment is applicable to a fully
functional system it finds application in systems where one or more
marking engines is not functioning normally and has either a fixing
shortfall or an image quality shortfall. In such instances, a
marking engine which in general has good image quality function,
but which is exhibiting a fixing shortfall, can be teamed with
another marking engine having good fixing capability but which may
be experiencing an image quality shortfall.
The scheduling system 110 receives information about the print job
or jobs to be performed and proposes an appropriate route for the
print media to follow in each of the jobs. The scheduling system
confirms with each of the system components, such as marking
engines, inverters, etc. that they will be available to perform the
desired function, such as printing, inversion, etc., at the
designated future time, according to the proposed schedule. Once
the route has been confirmed in this way, any fuser temperature
modifications are determined by the control system 92 and/or CPU 90
and the marking engine/fixing devices notified so the fixing device
will be at the appropriate temperature when the print media
arrives. Where the scheduling system has multiple jobs waiting in a
queue, the scheduling system may order the jobs in the queue to
minimize the time needed for fuser roll adjustments.
A job previewer or digital front end 114 in communication with the
image input source 100, 102 reviews incoming jobs and sends
information on the jobs to the scheduling system 110. This
information may include the number of pages to be printed on each
type of media, particularly identifying those pages to be printed
on sheets of heavy weight media, rough paper, or coated paper, the
image to be applied to each page of the sheet, and other
information to be used in scheduling the printing of the print
job.
The scheduling system 110 determines which, if any of the sheets
are to undergo a secondary fixing treatment and assigns appropriate
marking engines to perform the first and second fixing treatments,
respectively. In making the assignment the scheduling system takes
into account the availabilities of the marking engines and their
fixing and other capabilities. The scheduling system may
communicate with the marking engines and other components of the
printing system via a coordinator 116, which coordinates the
printing of the job including the transportation of the print media
to the marking engines, the marking of media, the secondary fixing
of selected media, where appropriate, and the collation and
assembly of print jobs output by the finisher according to the
scheduled itinerary.
A user input 118 optionally receives user inputs, such as user
preferences, which affect job scheduling. The user input 118 may be
connected to a suitable user input device (not shown) such as a
keyboard, selector switch or the like. The user input 118 may be
used to select between two or more modes which affect one or more
of (1) whether a secondary fixing treatment is applied; (2)
constraints on selection of a marking engine as the secondary
fixing device. For example, the user may select between: 1. A
normal (or default) mode, in which the scheduling system selects
any available marking engine as a secondary fixing device only in
instances where a single marking engine, under normal operating
conditions, is unable to achieve a preselected level of attachment
of the image to provide image permanence and/or a preselected
minimum gloss level; 2. One or more user selected modes in which
preselected criteria are used by the scheduling system in selecting
a marking engine to be used as a secondary fixing device.
For example, where a user places a high importance on achieving a
consistent gloss or a predefined (usually high) gloss level for a
particular print job, the user may select a user selected gloss
mode. In this mode, the scheduling system identifies a marking
engine which best meets the criteria associated with the user
selected gloss mode. In the gloss mode, the second fixing device
may be used to achieve the consistent/selected gloss even though
the first fixing device may provide adequate fixing for image
permanence purposes and a gloss level or gloss consistency which is
within acceptable limits as defined for the normal mode. Depending
on the preselected criteria, the scheduling system 110 may delay
the print job or make other changes to ensure that a marking engine
which meets the selection criteria is available for performing the
secondary fixing function.
The processing component, e.g., the model of the machine 112 or
marking engine CPU 92, includes information or algorithms from
which suitable adjustments to the set points of a fixing device
which is to be used as the second fixing device can be determined.
Set points which may be adjusted when a fixing device is to be used
as a secondary fixing device include operating temperature, dwell
time, and pressure set points. In general, the sheet temperature as
it reaches a second fixing device depends on such factors as the
temperature of the first fixing device, the time spent in travel
between the first and second fixing devices, and the basis weight
of the print media. Based on this information, adjustments may be
made to one or more of the set points of the secondary fixing
device to account for the heat provided by the sheet. Typically, a
fuser can be set at a lower temperature when it is to be used as a
secondary fixing device, thereby extending the useful lifetime of
the device. Alternatively, the residual heat of a marked and fixed
sheet may be utilized to achieve higher fixing or gloss without
lowering the temperature set point of the second fusing device. In
general, control of the fuser temperature set point to account for
incoming media temperature allows a more accurate control of the
gloss level of the image. In one aspect, part or all of the
function of controlling the fuser set points may be assumed by the
individual CPU 90 of the relevant marking engine. In this aspect,
the control system 92 directs the marking engine to serve as a
secondary fixing device and the marking engine's CPU 90 determines
appropriate adjustments to the set points.
The model of the machine 112 is periodically updated with
information on the current states of the marking engines 14, 16,
18, feeder 12, and finisher 20 by querying the marking engine CPU
90 (either directly or via the coordinator 116) and similar
processing components in the feeder 12 and finisher 20.
In one embodiment, the feeder 12 includes sensors which detect
paper properties, such as the weight, surface roughness, or gloss
of paper in the trays 24, 26, 28, 30. This information is
communicated to the model of the machine 112 and/or scheduling
system 110. Alternatively, this information may be fed to the
processing component by a user using the user input 118.
Various methods of scheduling print media sheets may be employed.
For example, U.S. Pat. No. 5,095,342 to Farrell, et al.; U.S. Pat.
No. 5,159,395 to Farrell, et al.; U.S. Pat. No. 5,557,367 to Yang,
et al.; U.S. Pat No. 6,097,500 to Fromherz; and U.S. Pat. No.
6,618,167 to Shah; U.S. application Ser. Nos. 10/284,560;
10/284,561; and 10/424,322 to Fromherz, all of which are
incorporated herein in their entireties by reference, disclose
exemplary scheduling systems which can be used to schedule the
print sequence herein, with suitable modifications.
It will be appreciated that. various of the above-disclosed and
other features and functions, or alternatives thereof, may be
desirably combined into many other different systems or
applications. Also that various presently unforeseen or
unanticipated alternatives, modifications, variations or
improvements therein may be subsequently made by those skilled in
the art which are also intended to be encompassed by the following
claims.
* * * * *